Iranian military forces on September 24 launched military exercises in an area near the border with Iraq's Kurdish autonomous region, a day before a controversial independence referendum in the northern Iraq region.

State broadcaster IRIB reports that the exercises in Iran’s Oshnavieh border region are part of annual events held to mark the beginning of the 1980-88 war between Iran and Iraq.

IRIB said the military exercises include artillery, armored vehicles, and airborne troops.

Meanwhile, Iran's state media reports that authorities in Tehran on September 24 halted all flights between Iran and Iraq's Kurdish region ahead of the referendum, at the request of the government in Baghdad.

"At the request of the central government of Iraq, all flights from Iran to Sulaymaniyah and Irbil, as well as all flights through our airspace originating from the Kurdistan region, have been stopped," Keivan Khosravi, the spokesman for Iran's Supreme National Security Council, said.

Clashes with Iranian Kurdish militant groups based in Iraq are fairly common in the border area.

Iran has joined Turkey and the Iraqi government in voicing opposition to the September 25 referendum in Iraq’s Kurdish region.

Turkey, battling its own Kurdish insurgency, has threatened military force to prevent the emergence of an independent Kurdish state on its borders.

Iraq’s government has warned that it will respond militarily to any violence resulting from the vote.

The United Sates and the United Nations have condemned the referendum.

The vote has raised concerns about instability across the region as fighting against the so-called Islamic State winds down in Syria and Iraq after a series of battlefield losses for the extremist militants.

Iraqi Kurds are expected to approve the September 25 referendum, but the nonbinding vote is not expected to result in any formal declaration of independence.